A chemical sensor for ozone based on an array of microfabricated tuning forks is described. The tuning forks are highly sensitive and stable, with low power consumption and cost. The selective detection is based on the specific reaction of the polymer with ozone. With amass detection limit of ~2 pg/mm2 and response time of 1 second, the sensor coated with apolymer sensing material can detect ppb-level ozone in air. The sensor is integrated into aminiaturized wearable device containing a detection circuit, filtration, battery and wirelesscommunication chip, which is ideal for personal and microenvironmental chemical exposuremonitoring.